Nicene and Ante-Nicene Fathers, Ser. II, Vol. XIV:The Canons of the Synods of Sardica, Carthage, Constantinople, and Carthage Under St. Cyprian, Which Canons Were Received by the Council in Trullo and Ratified by II. Nice.: Canon XCV

It seemed good that there should be no more the yearly necessity of fatiguing the brethren; but as often as common cause, that is of the whole of Africa, demands, that letters shall be given on every side to that see in this matter, that a synod should be gathered in that province, where the desirability of it induces; but let the causes which are not of general interest be judged in their own provinces.